Flexible spectrum use (FSU) generally refers to any spatially and/or temporally varying use of radio spectrum radio resources. The use of FSU for future wireless systems is intended to provide spectrum sharing between parties that participate actively in the communication process. In a FSU system devices are able to use the spectrum in a flexible manner by adapting their operation to the current situation by sensing the environment or based on pre-defined regulatory policies that can vary in time, place, code and/or event.
An FSU system arranges the sharing of spectrum resources in a self-organizing manner leading to an uncoordinated deployment of the various networks. In an uncoordinated deployment there is no overall control over the placement of access points (APs), nor is there any expectation of frequency planning or any other traditional network planning methods. As a result, user equipments (UEs) must process information received from different APs and decide the optimum AP to associate with by taking into account the knowledge of the FSU situation.